1. Field of the Invention
Embodiments of the invention generally relate to methods for depositing silicon-based materials. More specifically, the present invention relates to chemical vapor deposition techniques for fabricating multi-layer silicon nitride films.
2. Description of the Related Art
Silicon nitride films are commonly utilized in the fabrication of devices that form integrated circuits. These films must possess varying characteristics depending upon the particular application for which the film is being deposited. One characteristic that is critical to control for certain applications is film stress. For example, in some applications, it is desirable to form a silicon nitride film having a higher stress (as compared to an underlying silicon substrate) so as to improve electron mobility through the silicon. Such improved electron mobility increases the speed of an NMOS/NFET device.
In other applications, it is desirable to form a silicon nitride film having a lower stress (as compared to an underlying silicon substrate) so as to minimize dislocation of the layer from, for example, the underlying substrate or to minimize the formation of dislocations in the substrate itself. Such dislocations are detrimental to device functionality as they scatter electron/hole motion and/or enhance diffusion where it is undesirable to do so. In addition, present manufacturing techniques utilize different processing tools to fabricate the spacer structures, resulting in increased time and cost of these components.
Thus, there is a need in the art for an improved method for fabricating silicon nitride films.